Safety and Tolerability Study of MBS2320 in Healthy Subjects and Subjects With Rheumatoid Arthritis

The study will be conducted in 4 parts (parts A to D). The principal aim of this study is to obtain safety and tolerability data when MBS2320 is administered orally as single and multiple doses to healthy subjects (parts A to C). The effect of MBS2320 on the pharmacokinetics (PK) of the first-line rheumatoid arthritis (RA) therapy, methotrexate (MTX), and the effect of MTX on the PK of MBS2320, will also be evaluated in a cohort consisting of subjects with RA (Part D).